1. Technical Field
The present invention relates to a position detecting function-added projection display apparatus capable of projecting an image and optically detecting the position of a target object located on the projection side of the image.
2. Related Art
In electronic apparatuses such as cellular phones, car navigation systems, personal computers, ticket-vending machines, and banking terminals, recently, position detecting function-added display apparatuses in which a touch panel is disposed on the front face of an image generating device such as a liquid crystal device are used. In such position detecting function-added display apparatuses, information is input while an image displayed in the image generating device is being referred to. Such touch panels are configured as a position detecting device that is used for detecting the position of a target object within a detection area (for example, see JP-A-2001-142643 (FIG. 6)).
The position detecting device disclosed in JP-A-2001-142643 (FIG. 6) is an optical-type which has a configuration in which a detection area is set on the side of the image displaying surface in a direct-view-type display apparatus, and a plurality of light emitting diodes and a plurality of phototransistors are disposed on both sides of the detection area. In such a position detecting device, when a target object enters into the detection area, light is blocked by the target object. Accordingly, when the phototransistor for which the light is blocked is specified, the position of the target object can be detected.
In addition, a position detecting device in which a light transmitting plate is arranged on the input operation side of a direct-view-type display panel such as a liquid crystal panel and a light source and light sensing devices are disposed on a side opposite to the input operation side with respect to the light transmitting plate is proposed (for example, see U.S. Pat. No. 6,927,384).
In the position detecting device disclosed in U.S. Pat. No. 6,927,384, the position detecting light emitted from a light source is emitted to the input operation side through the light transmitting plate, and the position detecting light reflected by the target object is received by the light sensing devices.
Here, the inventor of the invention proposes a position detecting function-added projection display apparatus that displays an image on a screen member and detects the position of a target object on the front side (screen surface side) of the screen member.
However, when the configuration disclosed in JP-A-2001-142643 (FIG. 6) is employed in configuring the position detecting function-added projection display apparatus, a plurality of light emitting diodes or phototransistors is disposed around the screen member, which is not practical.
In addition, in the position detecting function-added projection display apparatus, it is practically impossible to arrange a light transmitting plate, a light source, or a light sensing device on the front side of the screen member. Accordingly, the configuration disclosed in U.S. Pat. No. 6,927,384 cannot be employed.